The corneal reflection technique is known as one of gaze detection technologies. The corneal reflection technique applies infrared light that is emitted from light sources to a subject, images, with cameras, the eyes of the subject to which the infrared light is applied, detects the positions of the pupils with respect to corneal reflection images that are reflected images of the light sources on the cornel surfaces, and detects the gaze of the subject. A gaze detection device using such a corneal reflection technique, for example, causes a display screen to display a still image or a moving image as a stimulus to a subject and causes a sound output device to output sound as the stimulus.
Patent Document 1: Japanese Laid-open Patent Publication No. 2016-187589 A
The above-described gaze detection device requires a configuration to efficiently adjust the timing of changing the mode in which sound is output. Furthermore, not only gaze detection devices but image sound output devices that output images and sounds require a configuration to efficiently adjust the timing of changing the mode in which sound is output.